SCHENECTADY, N.Y.: What kinds of memory lapses are part of normal aging, and which are cause for concern?
Aaron Philip Nelson, Ph.D.: All of our bodily systems acquire some "wear and tear" as part of the normal aging process: the brain is no different in this regard. Misplacing the car keys, forgetting the name of an acquaintance, or briefly losing track of what you were doing moving from one room to the next usually result from lapses in attention; they are not early symptoms of Alzheimer's disease or other forms of dementia. More concerning examples of memory failure would include difficulty remembering the name of a family member or close friend, forgetting a conversation you had a few minutes or hours ago, becoming lost or disoriented in a familiar environment such as your home or neighborhood, or forgetting how to use a common household appliance or tool. Alzheimer's disease - the most common form of dementia - typically begins to produce observable symptoms in the late 60s or early 70s (although the underlying disease process begins decades earlier). Extremely rare forms of the disease can manifest much earlier in life, but there are genetic markers and usually a clear family history for this kind. Abnormal changes in memory function can also be caused by a number of other conditions including depression, sleep disorders, nutritional deficiencies, and hormonal changes.
LOS ANGELES: Why do we forget dreams so easily?
Dreaming occurs episodically throughout sleep. Whether or not you remember a dream depends on whether or not you awaken directly from the dream state. Normal sleep is divided into a series of stages that we cycle back and forth between several times throughout the night. Most dreams occur during stage five sleep, or REM (rapid eye movement) sleep. If you awaken during Stage 2 sleep, for example, it is much less likely that you will remember a dream than if you awaken during or shortly after an REM cycle. If you want to remember your dreams, form the intention to do so in your mind as you lie down for sleep. Cue yourself with a post-it note in the first place you will look when you wake up. Keep a pen and paper beside your bed and start making notes as soon as you awaken, before doing anything else.
HAYDENVILLE, MASS.: Why is it that I have never been able to remember names?
This is probably the most common memory complaint I hear. Difficulty remembering names is not necessarily a sign of memory disorder. Remembering the name of someone you just met is actually quite difficult, unless you make a specific effort. When you meet someone for the first time there's usually a lot going on; the name comes to you in the midst of other information about the person, such as where they are from, and what they do for a living. On top of that, most names fall into the category of low-contrast information. The name Bill is not all that different than the name Bob or Tom or Joe; they are all members of a large category of single syllable, American male names. The failure to "remember" a name is usually a failure of attention, not a failure of memory. In other words, in order to remember something later on, you need to truly learn it in the first place. If this vital "front-end" process of encoding does not take place, then the name will not be there when you try and recall it later.
PHOENIX: Does our memory have a way of continuing to work outside our control? Often when I want to remember something I can't, but then it pops into my head days or weeks later.
Yes, when you fail to remember a name at a particular moment in time and you eventually give up and shift your focus to something else, the brain may keep the search going on a back-channel basis, running down fragments of information and tiny associations and linkages until Voila! Its only one of a staggering number of things the brain is capable of carrying out outside our conscious control. Conscious control requires attention, and we can only pay attention to a few things at a time.
STOLKHOLM, SWEDEN: People always talk about training the brain to remember, but for bad memories, is it possible to train the brain to forget?
It can be difficult for someone who has sustained severe psychological trauma to block out memories of the experience. Post-Traumatic Stress Disorder is a clinical syndrome in which the sufferer is beset by recurrent, intrusive memories of a traumatic event. The nature of the trauma can vary widely but the disorder is relatively common in the contexts of warfare, natural disaster, criminal assault, torture, personal injury or sustained entrapment in horrific conditions. There are a range of treatment approaches to PTSD. A number of such therapies entail controlled graduated exposure to traumatic memories and images in a safe environment, challenging irrational associated thoughts, modulating feeling states, and ultimately helping the individual integrate the traumatic experience into their life in a less evocative way. Scientists have also been studying techniques for preventing the formation of traumatic memory, through the use of certain drugs, like beta blockers. Such medication would dial down the physiologic "flight or fight" response that often accompanies trauma. The goal of this intervention would be to disrupt the future ability of the traumatic memory to evoke that physiological response. Approaches like this have generated a good deal of controversy, and as they develop, we will have to work through a variety of ethical issues, including whether or not such treatments risk normalizing behaviors that would be repugnant in everyday life.
ROCKFORD, Ill.: Why is it that when we check our watches for the time, if someone asks us what time it is right after, we have to glance at our watches again?
You probably don't have to glance at your watch again; you do it reflexively. But your question does raise an important point about the nature of memory. Memory is not a single, uniform process. We now know that there are several different forms of memory, each specializing in handling different types of information and each served by distinctive (though partially overlapping) regions and circuits within the brain. The memory you use to tell someone the time after you've checked your watch is known as "working memory." Working memory is the form of short-term memory we rely on to temporarily hold some information in mind which we need in order to complete a task. Looking up a phone number and keeping it in mind until you've dialed it; keeping a series of numbers in mind long enough to add them up. Once the task is accomplished, we turn our attention to something else and the information rapidly fades. This form of memory is highly sensitive to interference. If someone taps you on the shoulder while you're adding a column of numbers, you have to start over again. We have other long-term memory systems for handling learning and memory of skills (e.g., driving a car or typing on a keyboard), remembering factual knowledge (e.g., the capitol of New Jersey, the meaning of the word "snow"), and remembering specific events (e.g., what you had for dinner last night, your summer vacation last year). Memory for faces also seems to be a specific subtype of memory.